It's been a couple years. Shaved it on a whim, she said it wasn't her favorite and it reminded her of someone with cancer. I grew it back quickly (have gotten some short buzzes since). Am itching to go sly again though...
So by growing back after her comment, she has established (in her mind) that she can control your hair style choice. IME, ladies do not like to see change in their man that they do not initiate themselves. They see it as a security issue and immediately start to feel insecure in the relationship. They may not even be aware of it, they just experience the insecurity feeling. That is why you need to stick with head shaving (or any change) for a period of time for her to adjust. After the adjustment, changing back would bring up the same issues again.
BTW - this is not a negative comment on your wife, it is just how ladies are wired.
Another option to consider. You said you have done buzzes before. Start with a buzz and stick with it for a while (don't let it grow out). Then step it a bit closer once you think your wife has adjusted to the buzz. Keep doing this until you get to a no guard buzz. Once you maintain a no guard buzz, it is a small step that goes unnoticed by most when you transition to shaving.